A dog’s sense of smell is an extraordinary thing. We’ve always known that dogs have a way more powerful sense of smell than us. We’ve put that super sense to good use over the years, using dogs to help us detect hidden things like drugs and explosives, and even diseases like cancer. What else can a dog’s nose do? Recent research suggests that dogs can “tell time” by detecting changes in the smell of their environment as the hours pass.

An article in New York Magazine’s The Science of Us sheds light on this interesting story. Alexandra Horowitz from Barnard College’s Dog Cognition Lab explains how it works in her new book called Being a Dog. While humans are more visual and are comfortable telling time by the passage of the sun in the sky and how the light in a room changes, dogs detect the passing of time by how scents change over the course of a day.

They may detect certain natural changes in smell, like the way hot air rises over the course of a warm afternoon, or distinguish between the scent of something that happened in the past vs. something that’s about to happen. In fact, their noses are so sensitive that they probably detect many other subtle environmental changes that we can only guess at. And of course, any dog parent knows that they are wise to human-generated scents and what that means for them, such as the smell of coffee in the morning and their first walk of the day!